1. Field of the Invention
This invention relates to the field of orthodontics and, more particularly, to the fabrication of a physical model that serves as a guide for the proper placement of orthodontic appliances, especially brackets, on a patient's teeth when utilizing any of several indirect bonding techniques.
2. Description of Related Art
Orthodontics involves repositioning the teeth to correct a malocclusion. This repositioning can be accomplished using various forms of orthodontic appliances or apparatuses. Fixed orthodontic treatment generally involves the bonding or cementation of bands, brackets, and tubes (collectively “braces”) to the teeth. The brackets and tubes serve as “handles” by which gentle forces can be applied to the teeth. Archwires are placed into the bracket slots to achieve the basic alignment direction and forces. Various combinations of elastomeric, elastic, coil spring, and other devices can be used to provide additional, specific forces to the teeth. Proper placement of the brackets on a patient's teeth is one of the most significant determinants of effective tooth movement to the desired location.
The most common form of “braces” is brackets that are bonded to the surface of the teeth. Two techniques for placing brackets on a patient's teeth are direct bonding and indirect bonding. Direct bonding is an intraoral procedure in which orthodontic appliances are oriented by inspection and bonded individually to the tooth surface by the doctor or auxiliary personnel. Indirect bonding is basically a two-step process by which brackets are affixed temporarily to the teeth of a physical model for that specific patient and then transferred all together to the mouth by means of a molded matrix or transfer tray that captures their predetermined orientation and permits them to be bonded simultaneously.
Advantages of indirect bonding compared to direct bonding include more accurate bracket placement, improved access, simultaneous bonding of all brackets, shorter bonding appointment times, and less re-positioning of the brackets due to placement errors. Ideal bracket positioning is the goal that should reduce adjustments to the archwires. All of these advantages result in decreased chair time, decreased orthodontist time, less treatment time, and less patient discomfort.
However, orthodontists are still dissatisfied with available direct and indirect bonding because existing techniques do not allow the orthodontist to optimally position orthodontic appliances in three dimensions relative to the tooth surfaces. In particular, these techniques do not take into account all five positional elements of a patient's teeth: rotation, height, angulation (or tip), torque, and in-out. Further, these existing techniques of indirect bonding provide minimal guidance as to how the actual position of a bracket compares to the clinician-defined prescription.
Therefore, a need exists for a physical bonding model and a method of indirect bonding that assist with optimal positional alignment of the brackets on the patient's teeth by taking into consideration all five positional elements of a patient's teeth. A need also exists for a method that even more so decreases chair time, decreases orthodontist time, lessens treatment time and lessens patient discomfort.